Xerostomia is the subjective sensation of dry mouth and may be associated with diminished or deficient salivary secretion. Saliva and salivary flow help prevent the accumulation of microorganisms in the mouth (Nederfors et al. 1997). Saliva is also necessary for effective remineralization of teeth (Narhi et al. 1999). Salivary flow initiates digestion of foods and help dissolve and remove food particles from the mouth. Saliva also lubricates the mucosa of the mouth, facilitating speech, eating, and swallowing and preventing mechanical injury to the surfaces of the mouth. Xerostomia is a commonly occurring disorder and results in higher risk for oral complications.
Diverse symptoms and consequences have been associated with xerostomia. Symptoms include halitosis, soreness, oral burning, difficulty swallowing, and altered taste sensation. Xerostomia also causes dental disorders including oral mucous membrane ulcers, dental caries and periodontosis, oral infections and respiratory tract infections. Known causes of xerostomia include various diseases causing organic change of salivary glands; pathological changes of salivary glands caused by systemic diseases; damaged salivary glands owing to radiotherapy; HIV infection (AIDS); secretory hypofunction owing to aging; and effects of administration of various drugs. Mental fatigue or stress may also be factors. Various drugs also result in xerostomia as a side effect. Examples of drugs that may cause xerostomia include: diuretics such as trichloromethiazide and furosemide, hypotensors such as reserpine and clonidine hydrochloride, anticholinergic agents such as atropine sulfate, and antihistamines such as chlorphenylamine maleate. Other examples thereof include various expectorant/cough suppressants, anti-Parkinson drugs, psychotropic drugs, antidepressants, tranquilizers, muscle relaxants, opiates and other narcotics. Radiotherapy has become increasingly important for treating malignant tumors in oral surgery and otolaryngology fields, and almost inevitably causes damage to salivary glands by ionizing radiation. This damage can result in especially severe xerostomia. Medications are believed to be responsible for a significant proportion of cases of xerostomia, particularly in the elderly (Nedefors et al. 1997). The list of drugs that are believed to affect saliva levels includes more than 400 agents (Narhi et al. 1999).
Xerostomia is more common among older people and among women (Hochberg et al. 1998; Nederfors et al. 1997). In one study xerostomia was reported in 21.3% of the men and in 27.3% of women (Nederfors et al. 1996). In another study of elderly type-2 diabetic individuals, the prevalence of dry mouth was found to be 25% (Borges B C et al. 2010). The prevalence of xerostomia in varied populations ranges from 0.9% to 46% (Orellana, M. F. et al. 2006).
There are various therapies for the treatment of xerostomia, although many result in unfavorable side effects and limited efficacy (Cassolato, S. F. et al. 2003; Gupta, A. et al. 2006; Silvestre-Donat, F. J. et al. 2004). For example, malic and citric acid have been used as salivary stimulants. However, they had a demineralizing effect on tooth enamel (Anneroth, G. et al. 1980; Davies, A. N. 2000).